Handle bad input file.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@22194 e7fa87d3-cd2b-0410-9028-fcbf551c1848

StandAlone/StandAlone.cpp

@@ -254,6 +254,11 @@ bool CompileFile(const char *fileName, ShHandle compiler, int debugOptions, cons
 {
     int ret;
     char** shaderStrings = ReadFileData(fileName);
+    if (! shaderStrings) {
+        usage();
+        return false;
+    }
+
     int* lengths = new int[NumShaderStrings];
 
     // move to length-based strings, rather than null-terminated strings